Compatibility between aluminium nitride and nickel

In relation to the joining of aluminium nitride ceramics to metal, the reac tion products and the reaction mechanism between AIN and Ni have been inves tigated under a nitrogen or an argon atmosphere at temperatures of 1273-167 3 K. Using AIN-Ni powder mixtures, reaction rates were determined by thermo gravimetric analysis and the reaction products were examined by X-ray diffr action, The reaction between AIN and Ni occurred above 1250 K under both N- 2 and Ar atmosphere, Under Nz atmosphere, the reaction product was only a N i-Al solid solution, Under Ar atmosphere, at higher temperatures and on pro longed heating, the reaction product was changed in the following order: Ni -Al solid solution, Ni-Al(s.s.) + Ni3Al, Ni3Al, Ni3Al + NiAl and finally Ni Al. The initial rates of the reaction obeyed a linear rate law. Under both N-2 and Ar atmosphere, the rate constants and the activation energies (224 and 210 kJ/mol) showed comparable values, The reaction rate is thought to b e controlled by a chemical process, such as the dissociation of AIN, When t he Ni particles were covered with a reaciton layer, the rate obeyed a parab olic rate law, The rate constant under N-2 atmosphere was 2 orders of magni tude lower than that under Ar atmosphere, In the range of stability of Ni-A l(s.s.), the activation energy under N-2 atmosphere (124 kJ/mol) was almost identical to that under Ar atmosphere (127 kJ/mol). Under Ar atmosphere, t he activation energy for Ni3Al formation was 342 kJ/mol. The kinetics are p robably determined by solid-state diffusion through the reaction layer.